HbA1c – When as Low as Possible Is Too Low

You can't be too rich or too thin, according to the Duchess of Windsor. And some physicians believe you can’t lower your blood sugar or your blood pressure too low. Every few years there’s a new ‘target’ set for blood pressure or HbA1c levels. (The HbA1c value represents the average blood sugar level you have had over the previous 4 weeks.)

Other expert voices believe that reducing HbA1c levels below 7% is not ideal – in fact, it may even be harmful. An editorial in the British Medical Journal has summarized the evidence in favor of a more conservative approach in long-standing type 2 diabetics.

Dr Lehman, a family practitioner in Oxfordshire, UK, cites 3 important recent clinical studies. In the ACCORD study, intensive glucose lowering was associated with no evidence of fewer non-fatal heart attacks, stroke, or cardiovascular death in patients with a resultant average HbA1c of 6.4%; the control group had an average HbA1c of 7.5%. The ADVANCE study (average HbA1c of 6.4% vs. 7.3%) had a similar outcome, but there was a reduction in kidney complications (nephropathy). The third study, done in US Veterans, compared patients with HbA1c levels maintained at 6.9% or 8.4%. There were no significant differences between the groups in the frequencies of cardiovascular outcomes. And, we should remember, tighter blood sugar control measures are both more costly and likely to be accompanied by more episodes of hypoglycemia.

Ironically, the National Health Service in UK has just issued requirements that practitioners should treat to reduce the HbA1c in half their type 2 diabetic patients to below 7% in order to earn the same amount they are currently paid for reaching a target of 7.5%. This step will lead to increased use of insulin in thousands of patients, along with more monitoring and more hypoglycemic episodes. The evidence doesn’t point to the benefit of such a measure. We must hope that this approach doesn’t find favor in the USA, at least until more results from well-controlled studies are available.

Update on Tue, April 21, 2009 at 05:04AM by Robert Griffith

This blog had only been posted for 2 days when I saw an article in the Annals of Medicine that says much the same thing, only better.  They conclude: "Quality measures set too low,invite clinicians to ignore patient burden, context, and goals. Keeping levels between 7% and 7.5% seems reasonable and feasible for many patients."